When a ball spins off
the side of a clubface, it leaves with sidespin.
As it travels through the air it has a leading edge (heading forward,
into the wind) and a trailing edge (heading backward,
away from the wind).

The leading edge spins into
the oncoming air. Turbulence results. The turbulence
pushes
the ball toward the trailing side.

The trailing edge side of
the ball is heading away from the wind, there is negative
resistance and the ball is pulled to the trailing side.

If you slice...
The clubface is 'open'
and it's path is 'outside to inside.'

If you hook...
The clubface is 'closed'
and it's path is 'inside to outside'.

What you want...
Is a clubface that's 'square'
and on a straight path.

Result

Swing
Path

Clubface

Slice

<-
<-
<-

/
o/ /

Straight

<- <- <-

| o|
|

Hook

<-<-<-

\ o\
\

At impact, the ball is just trying to get
out of the way of the club. It takes the path of least resistance.
The more loft the clubface has, the more
likely the ball is to roll up the face instead of spinning off the
side.